it is still registered as a fire engine so free road tax and mot exempt so say the dvla,drives and pumps still work,so do the bluesand other fixings
I think, from the vague memory of a conversation I had with someone else who had one of these, that for the MOT exemtion you need to have the vehicle recorded with the fire service as an auxiliary vehicle - i.e. you may be called on to assist at some point. But there again an annual MOT isn't such a bad thing.
Should be tax exempt anyway as it's pre 73
Blues & twos are also probably only allowed if it's still in service, and there may well be additional regulations that apply.
There is probably an "ex fire engine" club, could be a good idea to find them and find out what the situation is.